1. Field of the Invention
The present invention relates to a process for producing alumina which can be converted to catalyst supports exhibiting enhanced resistance to loss of surface area when subjected to high temperatures.
2. Description of the Background
One of the key requirements of a catalyst support or substrate such as alumina (Al.sub.2 O.sub.3) is high surface area. Increased surface area allows for deposition of the catalytically active species, enhances reactivity between the catalytically active species and the reactants and, in general, makes for a more efficient catalyst support. In the case of catalyst supports of alumina used in catalytic converters for automobiles, i.e. autocatalyst supports, high surface area is particularly desirable because of short residence times between reactants and catalytic species, the desire to minimize the size of the catalytic converter and hence the need for a high efficiency catalyst.
A particular problem with autocatalyst supports involves the high temperatures to which the supports are subjected. High temperatures deleteriously effect the structural integrity of the catalyst support resulting in a loss of surface area. In effect, the elevated temperatures cause the catalyst to collapse on itself.
It is known that stabilizers such as oxides of barium and the lanthanide series of elements can stabilize autocatalysts in the sense that the loss of structural integrity of the support is retarded. In particular, oxides of barium, lanthanum or other lanthanide elements have been used in alumina based autocatalyst supports as heat stabilizers.